Human tuberculosis caused by Mycobacterium tuberculosis (M. tuberculosis) is a severe global health problem, responsible for approx. 3 million deaths annually, according to the WHO. The worldwide incidence of new tuberculosis (TB) cases had been falling during the 1960s and 1970s but during recent years this trend has markedly changed in part due to the advent of AIDS and the appearance of multidrug resistant strains of M. tuberculosis. 
In 1998 Cole et al published the complete genome sequence of M. tuberculosis and predicted the presence of approximately 4000 open reading frames (Cole et al 1998). Nucleotide sequences are described, and putative protein sequences. However importantly, this sequence information cannot be used to predict if the DNA is translated and expressed as proteins in vivo. More importantly, it is not possible on the basis of the sequences, to predict whether a given sequence will encode an immunogenic or an inactive protein. The only way to determine if a protein is recognized by the immune system during or after an infection with M. tuberculosis is to produce the given protein and test it in an appropriate assay as described herein.
Short term-culture filtrate (ST-CF) is a complex mixture of proteins released from M. tuberculosis during the first few days of growth in a liquid medium (Andersen et al., 1991). Culture filtrates has been suggested to hold protective antigens recognized by the host in the first phase of TB infection (Andersen et al. 1991, Orme et al. 1993). Recent data from several laboratories have demonstrated that experimental subunit vaccines based on culture filtrate antigens can provide high levels of acquired resistance to TB (Pal and Horwitz, 1992; Roberts et al., 1995; Andersen, 1994; Lindblad et al., 1997). Culture filtrates are, however, complex protein mixtures and until now very limited information has been available on the molecules responsible for this protective immune response.
It is thus an object of the present invention to provide a composition for the determination of an immune response against a virulent Mycobacterium such as a diagnostic reagent for the diagnosis of an infection with a virulent Mycobacterium. 